Establishing Due Date Per 2014 ACOG Recommendation 1. Agreement is needed between providers and patient
2. Last Menstrual Period (LMP) is used to estimate EDD when the following criteria are met:
Remembered accurately per patient
Menses regular and monthly
Not on hormonal contraception at the time or just before the last period
Ultrasound dates are consistent with the LMP (see below)
3. Earlier ultrasounds are almost always more accurate for establishing due date than later ultrasounds
Exception: Ultrasounds with measurement of the embryo crown rump length (CRL) are more accurate than gestational sac measurements—a 7 week CRL would be used over a 5 week gestational sac measurement
If a clinic or informal ultrasound seems inconsistent and a slightly later formal ultrasound exists, it is reasonable to use the later, formal ultrasound as less likely to have clinician error
Clinical situation and serial fetal growth ultrasounds may need to be considered In establishing the best EDD for a pregnancy being dated in the late second and third trimester
Criteria For Changing EDD established by reliable LMP because of ultrasound results
Based on ACOG Committee Opinion October 20, 2014
1. Agreement is needed between providers and patient
2. Last Menstrual Period (LMP) is used to estimate EDD when the following criteria are met:
3. Earlier ultrasounds are almost always more accurate for establishing due date than later ultrasounds
Criteria For Changing EDD established by reliable LMP because of ultrasound results
Based on ACOG Committee Opinion October 20, 2014